Considering the turbine in isolation provides a useful insight but without considering the engine as a whole it doesn't resolve the sort of matching issues (at any level) that we are likely to face.
Just changing the turbine on any engine is destined to a poor choice of action simply because everything else is tailored to the performance of the original not least of all the processing of thermal waste.
In terms of extracting a broader range of performance it strikes me that the turbocharger in general is misused. The optimal performance envelope for any given turbo is always limited and while we can attempt to broaden that envelope it is very hard to achieve and potentially very expensive - for the grassroots tuner likely to be beyond the realms of viable endeavour.
Two strategies spring to mind that can assist in mastering the potential of the turbo and developing a more useful output. The first of these is already in use with the VAG turbo petrol engines and relies on the use of an electronically controlled valve that effectively limits the dynamic compression ratio. The bane of turbo petrol engines is the need for a low CR (as already stated above) but this means that without the boost the engine is effectively just a low compression engine producing little torque. The most boost the less static compression the engine needs to prevent component failure. In a race engine that spends all of its time under load this is fine but suffers horrendously off boost (the top gear demonstration of how bad the Evo IX FQ behaved was a very graphic illustration). For a more versatile engine the static CR needs to be kept as high as possible though. A smaller turbo (in terms of mass flow) would lead to the engine staying within limits under dynamic compression but running out of puff at higher revs (which leads us back to why diesel turbos are so good). A larger turbo capable of providing sufficient mass flow across the desired rev range would be ideal but could potentially produce an excess while operating in its optimum performance envelope. The control valve wastes this excess keeping the boost under control and the dynamic compression where the engine can operate without risk of destroying itself.
The second possiblity is a more recent development for the road car and is apparent with the latest generation of engines due in the next year and gives a new meaning to dynamic compression ratio. The engine is capable of internally wasting excess compression and effectively performs the same task as the valve used by VAG. With the hardware integrated into the engine itself the need for an external valve is lost. This variable static compression ratio mechansim has the potential to assist with off-boost running to maintain more linear performance. Combined with the now ubiquitous variable cam timing it is possible to envisage an engine that can provide optimal performance in all respects - economic, low compression and lean burn for cruising with high performance on tap when required.
In terms of changing the requirements of matching the turbo to the engine little has changed (the engineer still has to make sure that everything works in unison) but the expectations of the consumer is more likely to be fulfilled. For fast road and race track applications both solutions have great potential (the variable compression ratio is not limited to forced induction making it of even greater interest). The reality of converting an existing design to variable compression is simply that it is unviable (for now) but the ability to effectively map boost is much more realistic.